The swf file format if very popular these days, as you can hardly visit a web
page without having some sort of advert or effect or even mini game displayed in
your web browser. Its also used in a variety of other places, such as in
the game industry and windows apps. As it allows you to display great
graphics which animate, showing cool menu intro's, ambients, and outro's...you
can mix in fonts etc, and its size is relatively small. So you can open up
macromedia and do a nice little bit of graphics, and then use your swf importer
to load it up in your app or browser! Easy as that.

Now this format isnt' for the weak hearted! Its a monster! Its
got all sorts going on in there, so that it does as much as possibly, and is
packed as small as possible. Its got a bigantua amount of information even
in the simplest file, including jpg images, animations, fonts, matrices.....it
can use compression, and it aligns lots of its data bit by bit (not byte
aligned)....

But well I'll give you the low down, and give you a kick start onto the road
of writing your own swf file parser!